In recent years, pharmaceutical chemists have worked to provide more specific and potent drugs for the treatment of disease. In the case of cancer and other disease which function by the creation of specific abnormalities of cells, most of the useful drugs have been of the cytotoxic type which function by killing the abnormal cell. Such drugs are quite potent and may be hazardous to the recipient, even life-threatening.
In an attempt to direct a drug to particular cells, tissues, or pathogen within a host, efforts have been made to develop a mechanism for targeting such drugs, particularly highly cytotoxic drugs, directly to the afflicted area or pathogen, without administering a whole-body dosage. However, no antibody-drug conjugate has been approved for therapeutic use. The present invention expands the scope of immunoconjugate technology by providing novel immunoconjugates useful for cell-/tissue-/pathogen-specific drug delivery in mammals and intermediates thereto.